The BitTorrent protocol provides one of the fastest ways to download large files from the internet, but to take advantage of it you need to install a torrent client. Transmission-Qt is one such client and it benefits from an extremely small resource footprint as well as the fact that it is incredibly easy to use.
Besides speed and low resource requirements, Transmission-Qt includes everything you would expect to find in a torrent client.
In addition to the program itself, there is also a web interface for download managements, peer exchange, support for magnet links, global and torrent by torrent speed limiting and much more.
One of the key benefits of Transmission over other torrent clients is the number of add-ons that are available. Browse through the add-ons directory and you will find everything from the ability to control torrents from your mobile to an updated web interface and much more.
Note that this is the Windows-only version of the Transmission project. This is the portable version.
There are a number of torrent clients to choose from, but Transmission's speed and extension options means that it is well worth a look.